Cat scratch colon is caused by barotrauma secondary to insufflation during colonoscopy

Over the past year we have read with interest several papers published in Endoscopy regarding what has been fittingly termed “cat scratch colon”. This condition is characterized by bright red linear markings that arise spontaneously and resemble scratches made by a cat. The term was coined by McDonnell et al. [1], who in their series of 8277 colonoscopies reported a prevalence rate of 0.25 % for these lesions. They found that the lesions occur in the ascending colon and are more common in women. Histological examination revealed the presence of collagenous colitis in three patients (14 %) and normal mucosa in the remaining 18 patients (86 %). The authors suspect that these lesions are secondary to barotrauma, although they were unable to confirm this hypothesis. More recently, both Katsinelos et al. [2] and Tominaga et al. [3] have reported cases of cat scratch colon, again in the right colon. Both ascribe the lesions to barotrauma while specifying that data to support this etiology are insufficient.

We have observed this type of lesion relatively often in diversion colitis. In these patients we have found such lesions both in the right colon and in defunctionalized rectal stumps.

Here we report a 60-year-old male patient who had undergone surgery for colorectal cancer and who underwent colostomy 15 months previously. Prior to reconstruction of the colon, the patient attended a check-up and underwent colonoscopy. During examination of the rectal stump we found an erythematous mucosa and a loss of vascular pattern, suggesting diversion colitis. When we withdrew the air we found that a small number of cat scratch lesions had appeared ([Fig. 1 a]). We insufflated air again without mobilizing the endoscope and observed an increase in the number of lesions ([Fig. 1 b]). Further lesions appeared after insufflating air a third time ([Fig. 1 c]). Histological examination of the colon was compatible with diversion colitis. The patient underwent surgery and currently remains asymptomatic.

Fig. 1 The rectal stump prior to colostomy showing cat scratch lesions. a Appearance following initial air insufflation. Further lesions developed following air insufflation a second (b) and third (c) time.

In our opinion, this case confirms that the cause of cat scratch colon is barotrauma due to air insufflation when the elasticity of the colon mucosa has been altered, regardless of the reason (in our case, diversion colitis, in others collagenous colitis or unknown causes).

Competing interests: None

References

• 1 McDonnell W M, Loura F, Pointon M J, Greenson J K. Cat Scratch colon.  Endoscopy. 2007;  39 459-461
• 2 Katsinelos P, Kountouras J, Chatzimavroudis G. et al . Cat Scratch colon: an impressive but innocent endoscopic finding.  Endoscopy. 2007;  39 1026
• 3 Tominaga K, Shigiyama F, Ito S. et al . Emergence of cat scratch colon during a colonoscopy.  Endoscopy. 2007;  40 353